Lancing devices are known in the medical health-care products industry for piercing the skin to produce blood for analysis. Typically, a drop of blood for this type of analysis is obtained by making a small incision in the fingertip, creating a small wound, which generates a small blood droplet on the surface of the skin.
Early methods of lancing included piercing or slicing the skin with a needle or razor. Current methods utilize lancing devices that contain a multitude of spring, cam and mass actuators to drive the lancet. These include cantilever springs, diaphragms, coil springs, as well as gravity plumbs used to drive the lancet. The device may be held against the skin and mechanically triggered to ballistically launch the lancet. Unfortunately, the pain associated with each lancing event using known technology discourages patients from testing. In addition to vibratory stimulation of the skin as the driver impacts the end of a launcher stop, known spring based devices have the possibility of firing lancets that harmonically oscillate against the patient tissue, causing multiple strikes due to recoil. This recoil and multiple strikes of the lancet is one major impediment to patient compliance with a structured glucose monitoring regime.
Another impediment to patient compliance is the lack of spontaneous blood flow generated by known lancing technology. In addition to the pain as discussed above, a patient may need more than one lancing event to obtain a blood sample since spontaneous blood generation is unreliable using known lancing technology. Thus the pain is multiplied by the number of attempts required by a patient to successfully generate spontaneous blood flow. Different skin thickness may yield different results in terms of pain perception, blood yield and success rate of obtaining blood between different users of the lancing device. Known devices poorly account for these skin thickness variations.
Variations in skin thickness including the stratum corneum and hydration of the epidermis can yield different results between different users. Spontaneous blood droplet generation is dependent on reaching the blood capillaries and venuoles, which yield the blood sample. It is therefore an issue of correct depth of penetration of the cutting device. Due to variations in skin thickness and hydration, some types of skin will deform more before cutting starts, and hence the actual depth of penetration will be less, resulting in less capillaries and venuoles cut and less spontaneous blood generation.
Known lancing devices fail to provide accurate sensing of lancet position. Thus they do not know exactly how far the penetrating member has cut into the tissue. This lack of position sensing is one reason for more painful lancing associated with known fluid sampling devices.
Additionally, known lancing devices fail to have sufficiently accurate control of lancet position and velocity to achieve a spontaneous blood generation in a relatively pain free manner.